The Animal Imaging Core provides individual projects with unique capabilities for detecting, localizing, and biologically characterizing primary and metastatic cancer cells in vivo in small-animal (i.e. rodent) models. This is accomplished through non-invasive imaging techniques such as gamma camera imaging and positron emission tomography (PET) of radiolabeled tracers (with phosphor-plate digital autoradiography and scintillation counting correlation) and magnetic resonance imaging and spectroscopy (MRI/MRS). Available resources include the microPET, an ultra-high-resolution smallanimal PET scanner. The current Core facility MRI/MRS instrumentation is the 4.7T 33 cm bore Omega CSI system; funding has been obtained to upgrade this system, as well as for the separate purchase of a 500-MHz wide bore (8.9 cm) self-shielded, vertical-bore 11.7T system, equipped with imaging gradients. With additional research space, acquisition of a third high-field, horizontal-bore magnet is anticipated. To optimize MRI/MRS data quality, experiments are individualized, including design and fabrication of specifically built coils and optimization of pulse sequence parameters. A "library" of such coils for different imaging experiments, specifically optimized for the size of the animal (mice/rat), the organ to be studied (superficial versus deep), the resolution required, and the number of animals to be studied, are now available. A microCAT small-animal CT scanner will soon be installed to provide ultrahigh-resolution anatomic images for registration with functional images. Besides facilities for animal dissection and necropsy, cell culture work, and histology, the Imaging Core also houses a new Microm 500M cryostatic microtome, an Olympus digital microscopy system, and a Waters dual-pump HPLC system for radiometabolite analyses. The Imaging Core also maintains a large library of advanced software packages. A "mini-PACS" is being developed to provide investigators real-time, center-wide access to small-animal imaging studies over our intranet.